Objective: To assess the prevalence and covariates of abnormal left ventricular (LV) geometry in diabetic outpatients attending Muhimbili National Hospital in Dar es Salaam, Tanzania. Methods: Echocardiography was performed in 61 type 1 and 123 type 2 diabetes patients. LV hypertrophy was taken as LV mass/height2.7 > 49.2 g/m2.7 in men and > 46.7 g/m2.7 in women. Relative wall thickness (RWT) was calculated as the ratio of LV posterior wall thickness to end-diastolic radius and considered increased if ≥ 0.43. LV geometry was defined from LV mass index and RWT in combination. Results: The most common abnormal LV geometries were concentric remodelling in type 1 (30%) and concentric hypertrophy in type 2 (36.7%) diabetes patients. Overall, increased RWT was present in 58% of the patients. In multivariate analyses, higher RWT was independently associated with hypertension, longer isovolumic relaxation time, lower stress-corrected midwall shortening and circumferential end-systolic stress, both in type 1 (multiple R2 = 0.73) and type 2 diabetes patients (multiple R2 = 0.66), both p < 0.001. These associations were independent of gender, LV hypertrophy or renal dysfunction. Conclusion: Increased RWT is common among diabetic sub-Saharan Africans and is associated with hypertension and LV dysfunction.